Improving the efficiency of internal-combustion engines is germane to reducing the rate of depletion of fossil fuels and to limiting or reducing the emission of carbon dioxide into the atmosphere. Its urgency is emphasized by increasingly stringent government mandates on fuel consumption. The best efficiencies presently publicly claimed for reciprocating internal combustion (IC) engines are approximately 40 percent. One well-known method of improving efficiency is to employ artifices whereby the effective compression ratio is less than the expansion ratio. The present invention emphasizes this technique and offers larger improvements than heretofore realized.
Reducing the emission of pollutants other than carbon dioxide in response to both air-quality concerns and potential adverse climatic effects is presently achieved by methods whose cost could potentially be lowered if the raw engine exhaust contained lower levels of pollutants requiring neutralization. One known means of limiting internal generation of pollutants is to minimize peak combustion temperatures. The present invention emphasizes the reduction of peak temperatures and reduction of the time spent at high temperatures within each cycle. The features of the invention directed to the reduction of peak temperatures consist in part of novel extensions of the existing methods known as exhaust-gas recirculation and lean-burn.